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=== tests/cases/compiler/genericCapturingFunctionNarrowing.ts ===
function needsToNarrowTheType<First extends { foo: string }, Second extends { bar: string }, SubFirst extends First, SubFirstMore extends First & {other: string}>(thing: First | SubFirst | SubFirstMore | Second) {
>needsToNarrowTheType : <First extends { foo: string; }, Second extends { bar: string; }, SubFirst extends First, SubFirstMore extends First & { other: string; }>(thing: First | SubFirst | SubFirstMore | Second) => void
>foo : string
>bar : string
>other : string
>thing : First | Second | SubFirst | SubFirstMore
if (hasAFoo(thing)) {
>hasAFoo(thing) : boolean
>hasAFoo : (value: First | Second) => value is First
>thing : First | Second | SubFirst | SubFirstMore
console.log(thing.foo);
>console.log(thing.foo) : void
>console.log : (...data: any[]) => void
>console : Console
>log : (...data: any[]) => void
>thing.foo : string
>thing : First | SubFirst | SubFirstMore
>foo : string
}
else {
// I would expect this to work because the type should be narrowed in this branch to `Second`
console.log(thing.bar); // Error: Property 'bar' does not exist on type 'First | Second'.
>console.log(thing.bar) : void
>console.log : (...data: any[]) => void
>console : Console
>log : (...data: any[]) => void
>thing.bar : string
>thing : Second
>bar : string
}
function hasAFoo(value: First | Second): value is First {
>hasAFoo : (value: First | Second) => value is First
>value : First | Second
return "foo" in value;
>"foo" in value : boolean
>"foo" : "foo"
>value : First | Second
}
}
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